Chap. IX] DESERTS 647 



iii. THE DESERT IN SOUTH AMERICA. 



The narrow western desert strip of South America from Peru to North 

 Chile has an extremely poor vegetation, the oecology of which has not been 

 investigated. The strip of desert to the cast oi the Andes in its Argentine 

 part represents a stunted form of the espinal-formation, except on the 

 extensive saline tracts, which possess a halophytic vegetation chiefly com- 

 posed of Salsolaceae. The following description by Niederlein 1 of the 

 southern, Patagonian, portion of this desert district gives some idea of the 

 conditions of existence of the vegetation, and deals with the associated 

 oecological peculiarities : — 



' One can understand the reason for the monotonous, that is the universally 

 stunted and severe, often forbidding, appearance of the vegetation. For here is the 

 dreary Patagonian formation, where, for thousands of square leagues, only dry grass 

 and loose sand mingled with salts are collected. A clear, cold, stern sky dominates 

 the scene. The sun scorches, and storms from the Cordilleras and winds from the 

 Antarctic Ocean sweep over the steppe and desert. Further north, and particularly 

 to the north-east, lies the usual battle-field on which the north or north-east wind 

 gains the victory. Rain seldom falls. Its water soon runs from the flat ridges into 

 the troughs and depressions of the wide plain, or into the salt-laden morasses of the 

 dune-valleys, if not into the lagoons of the enormously widespread sandy tracts. 

 Not a brook, not a rivulet meanders down to the few existing rivers ; and only 

 because the red and the black stream hurries the water from the mountain down 

 along a deep course do they reach the sea. The salt-water stream exhausts itself in 

 the midst of the desert. Even on the slopes of the Cordilleras, wherever erosion 

 has carved its mighty deeds of violence in millions of canadas, clefts, and ravines, one 

 looks in vain for tributary streamlets. Only during the rains does activity prevail in 

 these crevices. Then the water trickles, gushes, and foams in all directions. Grains 

 of sand are carried down in myriads, gravel is hurried along, and earth and rocks 

 are shattered. From the thousands of bubbling tributaries arise destructive brooks. 

 As torrents laden with rocky debris and other material, they burst through the chaos 

 of ravines, and falling into the swollen Nauquer river, which has greatly overflowed its 

 banks, they whirl impetuously and violently down to the sea. But when the cloud 

 has discharged its water, when the curtain of mist has been severed, and the sun- 

 light streams down upon the land, the waters dry up. A little later the former 

 condition of repose returns. Only the winds continue to blow. The ground rapidly 

 dries up, and soon the desert frowns as forbiddingly as before. Similar conditions 

 reign in the upper reach of the Rio Colorado. It is somewhat different at Payen 

 and along the Sierra Roca. Yet in places, where erosion exhibits no extraordinary 

 effects, where not a rivulet flows, where no mountains stand, the above description 

 is applicable to both steppe and desert. The territory depicted, with its dreary and 

 wild aspect, may thus be described as exhibiting broken and hilly slopes of the 

 Cordilleras, river-valleys, steppes, and deserts. 



' As has been stated, the vegetation admirably corresponds to the terrestrial and 

 physical features of the country. The few grasses are stiff, the perennial herbs are 



1 Niederlein, op. cit., p. 88. 



